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ZFS Automatic Snapshot Service for Linux
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| README.zfs-auto-snapshot.txt | ||
NAME ZFS Automatic Snapshot SMF Service, version 0.12 DESCRIPTION This is a simple SMF service which can will take automatic, scheduled snapshots of given ZFS filesystems and can perform simple incremental or full backups of those filesystems. Documentation for the service is contained in the manifest file, zfs-auto-snapshot.xml. Version 0.11 removes the simple GUI applications that were used to create manifests, or select which filesystems should be included in the canned instances. These are superceded by the time-slider-setup application. INSTALLATION To install, as root, pkgadd SUNWzfs-auto-snapshot. This package now contains several canned SMF instances. These are: online 1:17:43 svc:/system/filesystem/zfs/auto-snapshot:hourly online 1:17:46 svc:/system/filesystem/zfs/auto-snapshot:monthly online 1:17:46 svc:/system/filesystem/zfs/auto-snapshot:daily online 1:17:48 svc:/system/filesystem/zfs/auto-snapshot:frequent online 1:17:49 svc:/system/filesystem/zfs/auto-snapshot:weekly online 1:17:49 svc:/system/filesystem/zfs/auto-snapshot:event These instances use the special "//" fs-name to determine which filesystems should be included in each snapshot schedule. See the description for "fs-name" below. The included instances have the following properties: frequent snapshots every 15 mins, keeping 4 snapshots hourly snapshots every hour, keeping 24 snapshots daily snapshots every day, keeping 31 snapshots weekly snapshots every week, keeping 7 snapshots monthly snapshots every month, keeping 12 snapshots event no automatic snapshots taken, keeps all snapshots The :default service instance does not need to be enabled. Additional instances of the service can also be created, for example to group related sets of filesystems under a single service instance. The properties each instance needs are: zfs/fs-name The name of the filesystem. If the special filesystem name "//" is used, then the system snapshots only filesystems with the zfs user property "com.sun:auto-snapshot:<label>" set to true, so to take frequent snapshots of tank/timf, run the following zfs command: # zfs set com.sun:auto-snapshot:frequent=true tank/timf The "snap-children" property is ignored when using this fs-name value. Instead, the system automatically determines when it's able to take recursive, vs. non-recursive snapshots of the system, based on the values of the ZFS user properties. zfs/interval [ hours | days | months | none] When set to none, we don't take automatic snapshots, but leave an SMF instance available for users to manually fire the method script whenever they want - useful for snapshotting on system events. This is used by the svc:/system/filesystem/zfs/auto-snapshot:event instance. zfs/keep How many snapshots to retain - eg. setting this to "4" would keep only the four most recent snapshots. When each new snapshot is taken, the oldest is destroyed. If a snapshot has been cloned, the service will drop to maintenance mode when attempting to destroy that snapshot. Setting to "all" keeps all snapshots. zfs/period How often you want to take snapshots, in intervals set according to "zfs/interval" (eg. every 10 days) zfs/offset The time from the start of the current interval at which snapshots should be taken, expressed in seconds. For example to take snapshots hourly at 15 minutes into the hour, zfs/offset = 900 (60 sec. * 15) To take daily snapshots at 15:43, zfs/offset = 56580. zfs/snapshot-children "true" if you would like to recursively take snapshots of all child filesystems of the specified fs-name. This value is ignored when setting zfs/fs-name='//' zfs/backup [ full | incremental | none ] zfs/backup-save-cmd The command string used to save the backup stream. zfs/backup-lock You shouldn't need to change this - but it should be set to "unlocked" by default. We use it to indicate when a backup is running. zfs/label A label that can be used to differentiate this set of snapshots from others, not required. If multiple schedules are running on the same machine, using distinct labels for each schedule is needed - otherwise one schedule could remove snapshots taken by another schedule according to it's snapshot-retention policy. (see "zfs/keep") zfs/verbose Set to false by default, setting to true makes the service produce more output about what it's doing. zfs/avoidscrub Set to false by default, this determines whether we should avoid taking snapshots on any pools that have a scrub or resilver in progress. More info in the bugid: 6343667 need itinerary so interrupted scrub/resilver doesn't have to start over zfs/sep A character used to separate components of the snapshot name generated by the service. Set to '_' by default. (the original character ':' caused problems for CIFS clients) zfs/auto-include Set to true by default, this determines whether we should set a property on all new pools (pools where com.sun:auto-snapshot isn't already set) telling the system to automatically include all datasets in that pool in the default schedules. Setting to false will prevent newly imported pools from being snapshotted. An example instance manifest is included in this archive. ZFS PROPERTIES See the description of 'zfs/fs-name' above for details on the com.sun:auto-snapshot property, used to select datasets for inclusion into each snapshot schedule. The 'com.sun:auto-snapshot-desc' property is set on every snapshot taken by the service. Values for this property are not defined and are left to the individual user. The service sets a value of 'Missed snapshot' in this property when snapshots are taken on service start (due to a previous scheduled snapshot being missed) Similarly, users can invoke the method script with an optional string which is then set as a value to this property. eg. # /lib/svc/method/zfs-auto-snapshot svc:/system/filesystem/zfs/auto-snapshot:event "Samba connect" # zfs get com.sun:auto-snapshot-desc rpool/timf@zfs-auto-snap_event-2009-06-22-1240 NAME PROPERTY VALUE SOURCE rpool/timf@zfs-auto-snap_event-2009-06-22-1240 com.sun:auto-snapshot-desc Samba connect local SECURITY The service is run by a restricted role "zfssnap", which is created when installing the service if it doesn't already exist. It has the "ZFS File System Administration" RBAC Profile, as well as the solaris.smf.manage.zfs-auto-snapshot Authorization. In order to see what the service is doing, you can view the SMF log files in /var/svc/log for each service instance and syslog, with more detailed logging output being sent to syslog when the "zfs/verbose" option is enabled. SEE ALSO More background about this service, along with implementation comments can be found in web log posts at: http://blogs.sun.com/timf/entry/zfs_automatic_snapshots_prototype_1 http://blogs.sun.com/timf/entry/zfs_automatic_snapshots_smf_service http://blogs.sun.com/timf/entry/and_also_for_s10u2_zfs http://blogs.sun.com/timf/entry/smf_philosophy_more_on_zfs http://blogs.sun.com/timf/entry/zfs_automatic_snapshots_now_with http://blogs.sun.com/timf/entry/zfs_automatic_snapshot_service_logging http://blogs.sun.com/timf/entry/zfs_automatic_snapshots_0_8 http://blogs.sun.com/timf/entry/zfs_automatic_for_the_people http://blogs.sun.com/timf/entry/zfs_automatic_snapshots_0_10 http://blogs.sun.com/timf/entry/zfs_automatic_snapshots_0_11 http://blogs.sun.com/timf/entry/zfs_automatic_snapshots_0_12 The ZFS Automatic Snapshot SMF Service is released under the terms of the CDDL.